Transcript PPadua-Douglas,E. HMWK 2012-05-21 12199

May 18, 2012
Solving Rational Expressions
DO NOW: Solve. *Remember cross multiplication?
1.
2.
4 x 5

7
6
x 5

3 11
Test next Friday!
HW 9.6:
Pg. 509 #4-7,11-14, 23
Lesson 9.6 Solving Rational Equations
Example 1:
Step 1: Simplify
Get a common
denominator
2
2 p 1
1
 2

p  4 p  2p 8 p  2
2
2 p 1
( p  2)


( p  2) p  4 ( p  4)( p  2)
2p 4
2 p 1

( p  2)( p  4) ( p  4)( p  2)
Step 2: Solve
Since it is a proportion,
you can cross
4p 3
1

multiply
( p  2)( p  4)
( p  2)
Solve by cross multiplying…
Leave your answers
as factors…
4p 3
1

( p  2)( p  4) p  2
(4p
–
3)(p
–
2)
=
(p
–
2)(p
+
4)
To make things easier,
cancel out the p – 2 by
dividing to both sides.
Why can we do that?
Cancel to get variable
on one side
(p – 2) (p – 2)
4p – 3 = p + 4
7
p
3
Practice:
1.
8
9
5

 2
x  5 x  4 x  9 x  20
3.
14
10
122

 2
x3 x2 x  x6
2.
10
4
 2
2x 1 3
4.
7
3
19


3 x  5 12